ReflectiveMethod.java
/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.test.internal.platform.reflect;
import androidx.annotation.NonNull;
import androidx.annotation.RestrictTo;
import androidx.annotation.RestrictTo.Scope;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* Helper class for making more performant reflection method invocations.
*
* <p>Lazy initializes and caches Method object to attempt to reduce reflection overhead.
*
* @hide
*/
@RestrictTo(Scope.LIBRARY_GROUP)
public class ReflectiveMethod<T> {
private final String className;
private final String methodName;
private final Class<?>[] paramTypes;
private final Class<?> clazz;
// lazy init
private boolean initialized = false;
private Method method;
/**
* Creates a ReflectiveMethod.
*
* @param className the fully qualified class name that defines the method
* @param methodName the method name to call
* @param paramTypes the list of types of the method parameters, in order.
*/
public ReflectiveMethod(String className, String methodName, Class<?>... paramTypes) {
this.className = className;
this.clazz = null;
this.paramTypes = paramTypes;
this.methodName = methodName;
}
public ReflectiveMethod(Class<?> clazz, String methodName, Class<?>... paramTypes) {
this.className = null;
this.clazz = clazz;
this.paramTypes = paramTypes;
this.methodName = methodName;
}
/**
* Invoke the instance method.
*
* <p>See {@link java.lang.reflect.Method#invoke(Object, Object...)}
*
* @param object the object the underlying method is invoked from
* @param paramValues the arguments used for the method call
* @return the return value of the method
* @throws ReflectionException if call could not be completed
*/
public T invoke(Object object, Object... paramValues) throws ReflectionException {
try {
initIfNecessary();
return (T) method.invoke(object, paramValues);
} catch (ClassNotFoundException e) {
throw new ReflectionException(e);
} catch (InvocationTargetException e) {
throw new ReflectionException(e);
} catch (NoSuchMethodException e) {
throw new ReflectionException(e);
} catch (IllegalAccessException e) {
throw new ReflectionException(e);
}
}
/**
* Invoke th static method.
*
* <p>See {@link java.lang.reflect.Method#invoke(Object, Object...)}
*
* @param paramValues the arguments used for the method call
* @return the return value of the method
* @throws ReflectionException if call could not be completed
*/
public T invokeStatic(Object... paramValues) throws ReflectionException {
return invoke(null, paramValues);
}
private synchronized void initIfNecessary() throws ClassNotFoundException, NoSuchMethodException {
if (initialized) {
return;
}
method = getClazz().getDeclaredMethod(methodName, paramTypes);
method.setAccessible(true);
initialized = true;
}
@NonNull
private Class<?> getClazz() throws ClassNotFoundException {
if (clazz == null) {
return Class.forName(className);
} else {
return clazz;
}
}
}